What the Anesthesiologist Should Know before the Operative Procedure

Patients with shoulder instability problems are usually young, healthy individuals who are active in sports activities and daily life. First-time dislocations in patients over 40 years of age are frequently associated with rotator cuff tears. Before the operative procedure, the anesthesiologist should know:

The etiology of the instability (traumatic or atraumatic). If the instability is traumatic in nature, associated injuries should be elicited in the history and physical examination.

Whether the planned procedure is arthroscopic or open, as well as the extensiveness of repair. This will determine the length of the surgical procedure.

In what position the patient will be placed: "beach chair" versus lateral decubitus position.

Whether the surgeon considers muscle relaxation necessary.

1. What is the urgency of the surgery?

What is the risk of delay in order to obtain additional preoperative information?

These procedures are elective and patients should be in optimal medical condition preoperatively. The risk of delaying the procedure is ongoing laxity of the shoulder joint and possibility of recurrent subluxation or dislocation, which may require reduction.

2. Preoperative evaluation

Patients with shoulder instability are usually young and healthy adults, and preoperative assessment should confirm a high exercise tolerance. The most important information gleaned from the preoperative evaluation is the assessment of the patient's airway and knowledge of any previous anesthetic difficulties. This would have the greatest implication on the type of anesthetic offered to the patient.

3. What are the implications of co-existing disease on perioperative care?

In this population, coexisting disease is uncommon. With frequent repeated dislocations, chronic analgesic consumption and high tolerance might be a challenge.

b. Cardiovascular system

Coronary disease is highly unlikely, but a history regarding arrhythmias should be sought.

c. Pulmonary

Chronic disease is unlikely, but asthma, particularly exercise-induced, is possible. Ventilatory status in these cases should be assessed and medical management optimized.

d. Renal-GI:

Esophageal reflux disease (GERD) might be present and should engender the usual precautions if heavy sedation or general anesthesia is contemplated.

e. Neurologic:

Patients with back pain do not generally tolerate the beach chair position with only minimal sedation. General anesthesia should be added to the interscalene block for these procedures.

f. Endocrine:

Patients with diabetes mellitus should have their glucose level checked before and after the surgical procedure. For patients with brittle diabetes, intraoperative monitoring of glucose levels may be necessary.

g. Additional systems/conditions which may be of concern in a patient undergoing this procedure and are relevant for the anesthetic plan (eg. musculoskeletal in orthopedic procedures, hematologic in a cancer patient)

N/A

4. What are the patient's medications and how should they be managed in the perioperative period?

Patients may take all routine medications preoperatively with the exception of anticoagulants and antiplatelet drugs, which should have been discontinued.

h. Are there medications commonly seen in patients undergoing this procedure and for which should there be greater concern?

Again, since most of these patients are young and healthy, they are often not taking any medications regularly.

i. What should be recommended with regard to continuation of medications taken chronically?

N/A

j. How To modify care for patients with known allergies -

The medications to which the patient is allergic should be avoided and alternatives used.

The operating room and all anesthetic equipment should be prepared with latex-free products. The operating room should also be labeled so that anything brought into the room is checked for latex prior to entrance.

l. Does the patient have any antibiotic allergies- [Tier 2- Common antibiotic allergies and alternative antibiotics]

Common antibiotic allergies include penicillin and sulfa. Clindamycin and vancomycin are often used as alternatives to cefazolin for orthopedic procedures. A sulfa allergy would be a contraindication to the use of perioperative celecoxib.

m. Does the patient have a history of allergy to anesthesia?

If there is a history of allergy to anesthesia, the anesthetic agents to which the patient is allergic should be avoided and alternatives used.

5. What laboratory tests should be obtained and has everything been reviewed?

Besides an ECG for an older patient or a pregnancy test for a menstruating female, laboratory testing is usually not necessary. If a patient has an underlying illness that would usually require testing (i.e., preoperative glucose for a patient with IDDM), that should certainly be checked.

Intraoperative Management: What are the options for anesthetic management and how to determine the best technique?

The options for anesthetic management include:

Regional anesthesia: single shot or continuous catheter techniques

Interscalene block only

Interscalene block with MAC

Interscalene block with general anesthesia (LMA or ETT) (an ETT may be necessary if the surgeon requires muscle relaxation)

General anesthesia with LMA or ETT

Any of the aforementioned options is reasonable for a patient who is in the sitting position, but general anesthesia with an LMA or ETT (with or without an interscalene block) is usually better tolerated by patients who are in the lateral position.

Regional anesthesia

Peripheral nerve block

Benefits:Procedures of the shoulder, whether open or arthroscopic should ideally have an interscalene block as the major component of the anesthetic or to provide postoperative analgesia. Advantages of using an interscalene block can include avoidance of general anesthesia and postoperative nausea and vomiting that may occur, bypassing of phase 1 post-anesthesia care unit and a decreased need for oral analgesics postoperatively (with a single-shot block and even greater decrease with a continuous block).

Drawbacks:Disadvantages of the block include the likelihood of phrenic nerve block causing ipsilateral diaphragmatic paralysis, which may be problematic in patients with pulmonary disease. It can be a source of mild anxiety requiring reassurance.

Issues: An interscalene block is superficial and can be performed in patients on antiplatelet medications and anticoagulants especially if an ultrasound-guided technique is use. Patients must be reminded that up to 14% may have paresthesias and dysesthesias secondary to the block at 2 weeks post procedure, but should completely resolve within several weeks.

The volumes of local anesthetic used for interscalene block vary by the technique used to place them: 20-60 mL volumes have been described by physicians using paresthesia and nerve stimulator techniques, while 20-40 mL volumes are chosen by those practicing ultrasound-guided regional anesthesia. Local anesthetic agent is chosen by desired outcome. While bupivacaine 0.25% or ropivacaine 0.5% are frequently used when the goal of the block is postoperative analgesia, higher concentrations of the agents are chosen when the interscalene block is the primary anesthetic. If a continuous catheter is placed for postoperative analgesia, a dilute infusion solution (0.2% ropivacaine or 0.1% bupivacaine) is sufficient; a dose of 20 mL of 1.5% lidocaine can be injected at the outset to confirm catheter placement.

It is important, when using MAC sedation (propofol infusion, midazolam) with the interscalene block, to remind the surgeon to inject local anesthetic in the region of the posterior arthroscopic portal, which is not covered by the block. Also, if the nonoperative arm is placed across the lap, rather than on an armboard, the intravenous line should be placed in the hand or forearm to ensure that it will run.

General anesthesia

Benefits:Patients do not have awareness of surgical procedure or discomforts of any position; patients with severe GERD may require general anesthesia with an endotracheal tube for airway protection.

No general anesthetic technique is superior to another for these patients, although since these procedures are usually performed as ambulatory ones, agents that are associated with early discharge should be used.

Monitored anesthesia care

Monitored anesthesia care can be an adjunct to an interscalene block, but is not adequate alone for surgery.

6. What is the author's preferred method of anesthesia technique and why?

The addition of MAC or general anesthesia to the block is based on the position of the patient during the procedure, the patient's body habitus, and the anticipated duration of the surgery.

What prophylactic antibiotics should be administered?

Cefazolin is the current recommended prophylactic antibiotic; vancomycin or clindamycn is an alternative in the presence of allergy.

What do I need to know about the surgical technique to optimize my anesthetic care?

The "beach chair" for arthroscopic surgery has the following advantages: (1) ease of set-up, (2) lack of brachial plexus strain (no traction), (3) excellent intra-articular visualization for all procedures, and (4) ease of conversion should the procedure need to become an open one. The advantages of the lateral position include that the longitudinal and direct lateral suspension provided by traction allows greater distention of the glenohumeral joint and makes it easier to pass instruments for the repair.

What can I do intraoperatively to assist the surgeon and optimize patient care?

Although surgeons will often request hypotension to decrease bleeding and improve visualization during arthroscopic procedures, the anesthesiologist must be aware of the potential for cerebral ischemia in the beach chair position.

What are the most common intraoperative complications and how can they be avoided/treated?

Intraoperative complications are rare. The anesthesiologist must always be prepared to administer general anesthesia if the patient is not tolerating MAC. This can be challenging in the sitting or lateral positions, but LMAs are usually easily inserted in either situation.

Complications

Cardiac: Anesthesiologists must be aware of the potential activation of the Bezold-Jarish reflex during arthroscopic surgery in the sitting position. This likely occurs when a patient receives epinephrine in the block and/or in the irrigation solution and has a hyperdynamic response in a hypovolemic heart (from NPO status, orthostasis), resulting in hypotension and bradycardia. Metoprolol, but not glycopyrrolate, has been shown to prevent this response.

Pulmonary: Patients can have hemidiaphragmatic paresis from phrenic nerve block on the side of the interscalene block. This often gives the sensation of having difficulty breathing even though patients are breathing adequately. Phrenic nerve block most likely becomes a problem for patients who have underlying severe pulmonary disease, and it usually manifests prior to the postoperative period, i.e., preoperatively or intraoperatively.

Neurologic: As discussed above, 14% of patients who receive an interscalene block may have paresthesia and dysesthesias at 2 weeks postprocedure. These should completely resolve within several weeks.

a. Neurologic:

The use of the "beach chair" position for orthopedic surgical procedures is controversial. There have been case reports of cerebral ischemia leading to permanent neurologic dysfunction following shoulder procedures in which induced hypotension is used. Blood pressure decreases 0.77 mm Hg for every 1 cm that it is measured above the level of heart. Therefore, when measuring mean pressures from a blood pressure cuff on the arm or leg, one must consider the actual pressures delivered at the level of the circle of Willis.

Also, because the patient is placed in the beach chair position, there may be neurologic complications secondary to improper positioning. Care needs to be taken when positioning the patient:

Proper padding of pressure points

Anatomic positioning of the other extremities

Neutral positioning of the head and neck

b. If the patient is intubated, are there any special criteria for extubation?

There are no special criteria for extubation. The patient's trachea should be extubated at the end of the procedure when the patient is awake and has adequate pulmonary parameters.

c. Postoperative management

What analgesic modalities can I implement?

Local anesthetic (0.1% bupivacaine or 0.2% ropivacaine) can be administered with pumps that deliver a constant fixed dose with or without PCA options or variable fixed doses with or without PCA options that are decreased over the first few postoperative days. At these doses, patients still require supplemental oral analgesics and should be told to expect to need to take them. The use of multimodal analgesia including NSAIDs and acetaminophen will reduce opioid requirements. Recent studies suggest that higher doses of local anesthetic (0.3% ropivacaine) provide superior analgesia without decreasing motor strength but patients should be warned of potential motor block with all these doses.

Dexamethasone may be used in combination with long-acting local anesthetics, such as ropivacaine or bupivacaine, in single-shot peripheral nerve blocks in order to prolong the duration of analgesia by several hours.

What level bed acuity is appropriate?

These procedures are generally performed as ambulatory ones and patients can be sent home with indwelling brachial plexus catheters. .

What are common postoperative complications, and ways to prevent and treat them?

When sending patients home with indwelling catheters, instructions (written and oral) must be given to the patient and a caregiver. These should include how to protect the numb extremity and how to care for the catheter, including instructions for removal, signs and symptoms of local anesthetic toxicity and what to do should they arise, and there should be a phone number where patients concerns and questions can be addressed